1. Technical Field
The present invention relates to a load controller, and more particularly to a load controller that can be operated even during the failure of an input side.
2. Background Art
As such kind of a load controller, a device is disclosed in JP-A-2001-148294. In this device, a chopping wave is allowed to be generated by a chopping wave generating circuit and the chopping wave is compared with a fixed input (a drive instruction signal) supplied from an ECU 32 by a comparator of an input circuit so as to output a drive control signal whose level is changed by a constant frequency and a duty ratio to a load and PWM-control the load.
However, in the above-described load controller, when the comparator of the input circuit is brought into a failure, the drive control signal is not outputted. When the load is a head lamp of a vehicle, the lamp is not turned on to deteriorate a safety in traveling. Since the input circuit comes into contact with the external part of the device, a static electricity or a surging voltage is apt to enter so that the input circuit is brought into a failure with a high possibility. Thus, a load controller has been desired in which even when an input part in the device is brought into a failure, the load can be driven at least with the lowest level.